selfreadonly

Selfreadonly is a software design concept describing an object whose internal state becomes immutable after construction. The idea is that once an instance is created, its own fields cannot be modified by the object’s methods or by external code, except through explicit, controlled transitions that typically produce a new instance rather than altering the original one. The term is used in discussions about immutability and may not correspond to a formal language feature in all ecosystems.

Implementation approaches vary by language and context. Common strategies include declaring internal fields as private and providing only read-only accessors, marking fields as final or readonly in the language, and using defensive copying or copy-on-write techniques for any operation that would modify state. Some designs introduce an initialization phase after which mutation is disabled, or rely on factory methods to produce new instances rather than mutating existing ones. In languages with strong immutability support, such as certain functional subsets of Java, C#, TypeScript, or modern Kotlin, selfreadonly is often achieved by default through immutable data types.

In practice, selfreadonly supports invariants and predictable behavior, and can improve thread safety and reasoning about code. It can also complicate scenarios that require gradual reconfiguration or high-performance mutation, and may introduce overhead from creating new instances or managing lifecycle constraints. Careful design is needed to balance immutability guarantees with real-world use cases and performance considerations.

See also: immutability, functional programming, persistent data structures, thread safety.